virt-aa-helper: generate rules for gl enabled graphics devices

This adds the virt-aa-helper support for gl enabled graphics devices to
generate rules for the needed rendernode paths.

Example in domain xml:
<graphics type='spice'>
  <gl enable='yes' rendernode='/dev/dri/bar'/>
</graphics>

results in:
  "/dev/dri/bar" rw,

Special cases are:
- multiple devices with rendernodes -> all are added
- non explicit rendernodes -> follow recently added virHostGetDRMRenderNode
- rendernode without opengl (in egl-headless for example) -> still add
  the node

Fixes: https://bugs.launchpad.net/ubuntu/+source/libvirt/+bug/1757085Reviewed-by: NErik Skultety <eskultet@redhat.com>
Acked-by: NJamie Strandboge <jamie@canonical.com>
Signed-off-by: NChristian Ehrhardt <christian.ehrhardt@canonical.com>

src/security/virt-aa-helper.c

@@ -1062,6 +1062,20 @@ get_files(vahControl * ctl)
     for (i = 0; i < ctl->def->ngraphics; i++) {
         virDomainGraphicsDefPtr graphics = ctl->def->graphics[i];
         size_t n;
+        const char *rendernode = virDomainGraphicsGetRenderNode(graphics);
+
+        if (rendernode) {
+            vah_add_file(&buf, rendernode, "rw");
+        } else {
+            if (virDomainGraphicsNeedsAutoRenderNode(graphics)) {
+                char *defaultRenderNode = virHostGetDRMRenderNode();
+
+                if (defaultRenderNode) {
+                    vah_add_file(&buf, defaultRenderNode, "rw");
+                    VIR_FREE(defaultRenderNode);
+                }
+            }
+        }
 
         for (n = 0; n < graphics->nListens; n++) {
             virDomainGraphicsListenDef listenObj = graphics->listens[n];

tests/virt-aa-helper-test

@@ -378,6 +378,12 @@ testme "0" "input dev passthrough" "-r -u $valid_uuid" "$test_xml" "$disk2.*rw,$
 sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,<memory>524288</memory>,<memory>1048576</memory>,g" -e "s,</devices>,<memory model='nvdimm'><source><path>$disk2</path></source><target><size unit='KiB'>524288</size><node>0</node></target></memory></devices>,g" "$template_xml" > "$test_xml"
 testme "0" "nvdimm" "-r -u $valid_uuid" "$test_xml" "$disk2.*rw,$"
 
+sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,</devices>,<graphics type='egl-headless'><gl rendernode='/dev/dri/testegl1'/></graphics></devices>,g" "$template_xml" > "$test_xml"
+testme "0" "dri egl" "-r -u $valid_uuid" "$test_xml" "/dev/dri/testegl1.*rw,$"
+
+sed -e "s,###UUID###,$uuid,g" -e "s,###DISK###,$disk1,g" -e "s,</devices>,<graphics type='spice'><gl enable='yes' rendernode='/dev/dri/testegl2'/></graphics></devices>,g" "$template_xml" > "$test_xml"
+testme "0" "dri spice" "-r -u $valid_uuid" "$test_xml" "/dev/dri/testegl2.*rw,$"
+
 testme "0" "help" "-h"
 
 echo "" >$output